Method of using a toner as a printable adhesive

ABSTRACT

Methods of using a toner as a printable adhesive are provided. In embodiments, a method of adhering substrates is provided which comprises disposing a cold pressure fix toner comprising a phase change material on a first substrate via xerography to form an unfused layer of the cold pressure fix toner on the first substrate; placing a second substrate on the unfused layer of the cold pressure fix toner; and subjecting the cold pressure fix toner to a pressure to form a bonded article comprising the first substrate, an adhesive layer formed from the cold pressure fix toner, and the second substrate. Methods of applying an adhesive to a substrate and bonded articles are also provided.

BACKGROUND

Adhesives are widely used for labeling and packaging, in laminatingobjects such as paper, plastic, wood, and metal, as well as inelectronics manufacturing where specialty adhesives are applied for theassembly of electronic components. For example, adhesives are used tocreate permanent or temporary graphic overlays, security documents, anddecals. These adhesives are typically pre-applied on the desired partsusing conventional coating or screen printing techniques, which areassociated with high materials usage, high tolling and handling costs,and long production cycle time. In addition, the screen printableadhesives contain solvent media or low molecular weight monomers, whichrequire drying or a curing step. Therefore, there is a need for a methodfor applying adhesives, which allows disposing the adhesive selectivelyon the surface on-demand, where the bonding is required, using digitalprinting techniques.

SUMMARY

The present disclosure provides illustrative examples of methods ofusing a toner as a printable adhesive.

In one aspect, methods of adhering substrates are provided. Inembodiments, a method comprises disposing a cold pressure fix tonercomprising a phase change material on a first substrate via xerographyto form an unfused layer of the cold pressure fix toner on the firstsubstrate; placing a second substrate on the unfused layer of the coldpressure fix toner; and subjecting the cold pressure fix toner to apressure to form a bonded article comprising the first substrate, anadhesive layer formed from the cold pressure fix toner, and the secondsubstrate.

In another aspect, methods of applying an adhesive to a substrate areprovided. In embodiments, the method comprises providing a cold pressurefix toner comprising a phase change material comprising a mixture of alow T_(g) amorphous resin having a T_(g) of less than about 10° C. and acrystalline organic material having a T_(m) in a range of from about 30°C. to about 130° C., and further wherein the cold pressure fix toneroptionally comprises a high T_(g) amorphous resin having a T_(g) in arange of from about 40° C. to about 70° C.; disposing the cold pressurefix toner on a substrate via xerography to form an unfused layer of thecold pressure fix toner on the substrate; and applying a pressure in arange of from about 25 kgf/cm² to 400 kgf/cm² to the unfused layer ofthe cold pressure fix toner to form an adhesive layer on the substrate.

In another aspect, bonded articles are provided. In embodiments, abonded article comprises at least two substrates and an adhesive layerdisposed in between the two substrates, the adhesive layer formed from acold pressure fix toner comprising a phase change material comprising amixture of a low T_(g) amorphous resin having a T_(g) of less than about10° C. and a crystalline organic material having a T_(m) in a range offrom about 30° C. to about 130° C., and further wherein the coldpressure fix toner optionally comprises a high T_(g) amorphous resinhaving a T_(g) in a range of from about 40° C. to about 70° C.

DETAILED DESCRIPTION

The present disclosure provides illustrative examples of methods ofusing a toner as a printable adhesive, e.g., to bond together varioussubstrates to form bonded articles. The present methods involve certaincold pressure fix toners. As used throughout this patent specification,“cold pressure fix toner” refers to toners specifically designed forapplication to a substrate followed by fixing to the substrate primarilyby the application of pressure, i.e., as opposed to by heating. Thepresent methods also involve application of the cold pressure fix tonersvia xerography, e.g., via a xerographic printer. Thus, at least someembodiments of the present methods are more flexible, less complex, andless costly as compared to conventional coating and screen printingtechniques for applying adhesive compositions. In addition, at leastsome embodiments of the present methods allow for the bonding of agreater variety of substrates as compared to the conventional methods.

As used throughout this patent specification, M_(n) refers to numberaverage molecular weight and M_(w) refers to weight average molecularweight, both of which may be measured by Gel Permeation Chromatography(GPC). The term T_(g) refers to glass transition temperature, which maybe measured by differential scanning calorimetry (DSC). The term T_(m)refers to melting temperature which may be measured by DSC.

In an embodiment, a method is provided which comprises disposing a coldpressure fix toner on a first substrate via xerography to form anunfused layer of the cold pressure fix toner on the first substrate,placing a second substrate on the unfused layer of the cold pressure fixtoner, and subjecting the cold pressure fix toner to a pressure. Asfurther described below, the pressure may be selected to convert thecold pressure fix toner to an adhesive layer in order to bond the firstand second substrates together to form a bonded article. Prior toplacing the second substrate on the unfused layer of the cold pressurefix toner, an initial pressure may be applied to the unfused layer ofthe cold pressure fix toner to partially fix the layer. During thebonding step or after the bonding step, heat may optionally be appliedto facilitate the bonding of the first and second substrates.

Cold Pressure Fix Toners

A variety of cold pressure fix toners may be used in the presentmethods. In embodiments, the cold pressure fix toner comprises a phasechange material comprising a mixture of a low T_(g) amorphous resinhaving a T_(g) less than about 10° C. and a crystalline organic materialhaving a melting point in a range from about 30° C. to about 130° C. Thelow T_(g) amorphous resin may have a T_(g) in a range from about 10° C.to about −45° C. In embodiments, the cold pressure fix toner may furthercomprise a high T_(g) amorphous resin having a T_(g) in a range of fromabout 40° C. to about 70° C.

The cold pressure fix toner may optionally comprise a shell covering thephase change material to provide suitable toner charging properties andstorage stability. The shell may comprise a high T_(g) amorphous resinin the range of from about 40° C. to about 70° C. In the case where ahigh T_(g) amorphous resin is also included in the phase changematerial, the high T_(g) amorphous resin in the shell may the same ordifferent as the high T_(g) amorphous resin in the mixture.

In embodiments, the cold pressure fix toner comprises a phase changematerial comprising a mixture of a low T_(g) amorphous resin having aT_(g) in a range from about 10° C. to about −45° C., a crystallineorganic material having a melting point in a range from about 30° C. toabout 130° C., and optionally a high T_(g) amorphous resin having aT_(g) in a range of from about 40° C. to about 70° C. Such a phasechange material may undergo a change in physical state from a solid formto a flowable phase at a modest temperature, such as from about 15° C.to about 70° C., at a pressure at as low as from about 25 kgf/cm² toabout 400 kgf/cm², or from about 50 kgf/cm² to about 200 kgf/cm².

In embodiments, the phase change material undergoes a change in physicalstate from a solid form to a flowable phase having a viscosity lowerthan about 10⁴ Pa·s at a temperature in a range of from about 10° C. toabout 90° C., at a pressure in the range of from about 10 kgf/cm² toabout 100 kgf/cm². It is highly desirable that the toner particles donot stick together, for example in the toner cartridge during storage orshipping, or inside the printer, including in the developer housing, oron the imaging surfaces such as the photoreceptor or the intermediatetransfer belt. In embodiments, the temperature required to lower theviscosity of the phase change material to about 10⁴ Pa·s at a pressureof about 25 kgf/cm² or lower, or about 10 kgf/cm², is from about 50° C.to about 90° C. In embodiments, the temperature required to lower theviscosity of the phase change material to about 10⁴ Pa·s at a pressureof about 100 kgf/cm² or higher is from about 10° C. to about 70° C. orfrom about 15° C. to about 50° C.

Low T_(g) Amorphous Resin

In embodiments, the low T_(g) amorphous resin may include an acrylicpolymer, an ethylene-vinyl acetate polymer, a styrene-acrylatecopolymer, a styrene-butadiene-styrene copolymer, astyrene-ethylene/butylene-styrene copolymer, astyrene-ethylene/propylene copolymer, a styrene-isoprene-styrene, apolyvinyl ether, a polyester resin, and the like, and combinationsthereof.

In a specific embodiment, the low T_(g) amorphous resin is a rosinacid-based polyester resin having Formula I:

wherein R¹ is a rosin acid of an abietic acid, a pimaric acid, orcombinations thereof, R² is (CH₂)_(n), wherein n is an integer from 2 to8, including 2 to 6 and 3 to 6; A, B, C, and D are independentlyhydrogen or methyl; and m is an integer from 10 to 10,000.

In embodiments, the M_(n) of the amorphous polyester is from about 300to about 1200, and the M_(w) is from about 300 to about 2,000.

The low T_(g) amorphous rosin acid-based polyester resins may beobtained by reacting a commercial rosin acid product (which may comprisecompounds having the formula C₁₉H₂₉COOH as exemplified by the family ofabietic and/or pimaric acids, any of which are optionally hydrogenated,and mixtures thereof derived from tree resins) with a glycol diglycidylether to afford a rosin-diol which is then polymerized with aliphaticdiacids to provide rosin acid-based polyester resins (I) with low T_(g)as indicated below in Scheme 1:

In embodiments, in compounds of Formula I, m is an integer from 10 to10,000, or 10 to 5,000, or 10 to 1,000, or 10 to 500, or 10 to 100. Inembodiments, m is an integer from 100 to 10,000, or 500 to 10,000, or1,000 to 10,000, or 5,000 to 10,000.

Depending on the length of the aliphatic diacid component, very low tolow T_(g) resins can be obtained as demonstrated in Table 1 below.

TABLE 1 Rosin acid-based polyester resins. A.V. M_(n) M_(w) DiacidViscosity (mg T_(g) (kg/ (kg/ Resin (R₂) (poise) KOH/g) (° C.) mole)mole) A/B = Me Sebacic; 15 13.5 −43.8 4.8 17.3 C/D = H R═(CH₂)₈ A/B = MeSuccinic; 61.8 12.8 −6.5 3.7 15.7 C/D = H R₂═(CH₂)₂

The rosin acid-based polyester resins may use an aliphatic diacidcomponent having from 3 to 20 carbons, 3 to 14 carbons, or 4 to 10carbons. In embodiments, the glycol diglycidyl ether is based on1,1-dimethyl ethylene glycol.

In embodiments, the rosin acid-based polyester resin has Formula I(above) wherein R¹ is an abietic acid, a pimaric acid, or combinationsthereof; R² is (CH₂)_(n), wherein n is an integer from 2 to 8; A, B, C,and D are independently selected from hydrogen and methyl; and m is aninteger from 10 to 10,000. In embodiments, R¹ is selected fromdehydro-abietic acid, neo-abietic acid, levo-pimaric acid, pimaric acid,sandaracopimaric acid, iso-pimaric acid, tetrahydro abietic acid andcombinations thereof.

In embodiments, the rosin acid-based polyester resin has a T_(g) in therange of from about 10° C. to about −45° C. (including from about 0° C.to about −45° C. and from about −5° C. to about −45° C.).

In embodiments, the rosin acid-based polyester is formed as follows. A2-L buchi reactor may be charged with 356.8 g Foral AX (Rosin Acid,available from Pinova), 166 g of neopentyl glycol diglycidyl ether(available from Sigma-Aldrich), and 0.57 g of tetraethyl ammoniumbromide (available from Sigma-Aldrich). The mixture may be heated to175° C. over a three hour period with stirring under nitrogen, and thenmaintained at 175° C. for five more hours and until the acid value ofthe resulting rosin-diol (see Scheme 2) is 1.8 mg of KOH/g of resin. Tothe mixture may be added 306 g propylene glycol (available fromArcher-Daniels Midland), 844.5 grams of sebacic acid (available fromSigma-Aldrich) and 2 g of TC400 catalyst (available from Elf-Atochem).The mixture may be slowly heated to 195° C. over a six hour period,followed by vacuum distillation until the resin viscosity is 15 and acidvalue of 13.5 mg of KOH/g of resin are obtained. The resin may bedischarged and allowed to cool to room temperature.

Crystalline Organic Material

In embodiments, the crystalline organic material is an ester compound(including a diester compound) or a crystalline polyester. The diestercompound may be a substituted phenyl or benzyl diester. Illustrativesuch diesters are listed in Table 2, below.

TABLE 2 Illustrative diester compounds. T_(m) T_(crys) T_(g) Structure(° C.) (° C.) (° C.)

94 47 n/a

115 62 n/a

74 ~50 n/a

102 51 n/a

86 34 n/a

35 n/a n/a

127 75 n/a

59 20-26 n/a

100 62 n/a

56 −5 n/a

119 ~75 n/a

80 18 n/a

80, 83 63 n/a

71 21 n/a

87 ~50 n/a

69 42 n/a

58 3 n/a

88 79 n/a

95 82 n/a

110 83 n/a

In embodiments, it may be desirable to incorporate one or more acidgroups, such as carboxylate or sulfonate, in the compounds of Table 2 toprovide negative charge to enhance toner performance. These acid groupsmay also be useful so the materials may be employed inemulsion/aggregation processing to form the cold pressure fix toner. Inembodiments, the acid moiety may be disposed in any position on thearomatic residues of the compounds in Table 2. In embodiments, the acidmay be provided by including some amount of the monoester in place ofthe diester so that one end of the molecule bears an acid moiety.

In embodiments, the crystalline organic material is a diester compoundmade from Scheme 2 below.

wherein R is a saturated or ethylenically unsaturated aliphatic group.In embodiments, R has at least 6 carbon atoms, at least 8 carbon atoms,no more than 100 carbon atoms, no more than 80 carbon atoms, or no morethan 60 carbon atoms.

In embodiments, the diester compound is derived from natural fattyalcohols such as octanol, stearyl alcohol, lauryl alcohol, behenylalcohol, myristyl alcohol, capric alcohol, linoleyl alcohol, and thelike. Scheme 1 may be conducted by combining dimethyl terepthalate andalcohol in the melt in the presence of a tin catalyst, such as dibutyltin dilaurate (Fascat 4202) or dibutyl tin oxide (Fascat 4100); a zinccatalyst, such as Bi cat Z; a bismuth catalyst, such as Bi cat 8124 orBi cat 8108; or a titanium catalyst such as titanium dioxide. Only tracequantities of catalyst are required for the process. In embodiments, thecatalyst is present in an amount in the range of from about 0.01 weight% to about 2 weight % or from about 0.05 weight % to about 1 weight %(based on the total weight of the product). The reaction may be carriedout at an elevated temperature of from about 150° C. to about 250° C. orfrom about 160° C. to about 210° C. The solvent-free process isenvironmentally sustainable and eliminates problems with byproducts andalso means higher reactor throughput.

In embodiments, the crystalline organic material may have Formula II:

wherein p1 is from 1 to 40, and q1 is from 1 to 40. In embodiments, p1is from 8 to 26, from 14 to 20, or from 16 to 18. In embodiments, q1 isfrom 8 to 26, from 14 to 20, or from 16 to 18. In embodiments, p1 is thesame as q1.

In embodiments, the crystalline organic material is a polyester.Crystalline polyesters may be prepared from a diacid (or a diesterthereof) and a diol. Examples of organic diols include aliphatic diolshaving from 2 to 36 carbon atoms, such as 1,2-ethanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,1,12-dodecanediol, and the like.

Examples of organic diacids include oxalic acid, succinic acid, glutaricacid, adipic acid, suberic acid, azelaic acid, sebacic acid,dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid,napthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid,cyclohexane dicarboxylic acid, malonic acid and mesaconic acid, or adiester or anhydride thereof. The organic diacid may be selected in anamount of, for example, from about 40 to about 50 mol % of the resin.

By way of illustration, crystalline polyesters have been prepared using1,12-dodecanedioic acid and diols from C3 (1,3-propylene glycol) to C12(1,12-dodecanediol). The crystalline polyesters exhibit values of T_(m)from about 60° C. to about 90° C. Illustrative crystalline polyestersare shown in Table 3, below.

TABLE 3 Illustrative crystalline polyesters. AV mg T_(m) GPC KOH/g (°C.) (g/m × 1000) Resin ID Acid:Diol resin 1st M_(w) M_(n) A C12:C9 10.371.0 24.2 6.8 B C12:C6 14.5 72.3 14.3 6.1 C C12:C3 17 66.1 13.4 6.6

In embodiments, the crystalline polyester is characterized by a T_(m) inthe range of from about 30° C. to about 130° C. (including from 40° C.to about 100° C. and from 50° C. to about 90° C.). In embodiments, thecrystalline resin is characterized by a M_(n) of from about 1,000 toabout 10,000. In embodiments, the crystalline resin is characterized bya M_(w) in the range of from about 2,000 to about 30,000.

In embodiments, the crystalline polyester component is present in thecore of the cold pressure fix toner in an amount of from about 20% toabout 60% by weight of the total weight of the core.

In embodiments, the weight ratio of the crystalline resin to anamorphous component (e.g., the low T_(g) amorphous resin) in the coldpressure fix toner is from about 50:50 to about 95:5, from about 60:40to about 95:5, or from about 70:30 to about 90:10.

High T_(g) Amorphous Resin

A variety of resins may be used for the high T_(g) amorphous resincomponent of the cold pressure fix toners. The T_(g) of the high T_(g)resin is generally greater than that of the low T_(g) amorphouspolyester resin. The T_(g) of the high T_(g) resin is also generallysufficiently high so as to enable blocking and other desired xerographicproperties of the cold pressure fix toner. In embodiments, the highT_(g) amorphous resin has a T_(g) in a range of from about 40° C. toabout 70° C. (including from about 50° C. to about 70° C. or from about55° C. to about 65° C.). As noted above, the high T_(g) resin may beused to form a shell over the core of the cold pressure fix tonerparticles. However, an amount of the high T_(g) resin may also beincluded within the core. In embodiments, the high T_(g) resin ispresent in the core of the cold pressure fix toner in an amount of fromabout 10% to about 30% by weight of the total weight of the core.

In embodiments, the high T_(g) resin is a styrene acrylate polymer. Thestyrene acrylate polymer may be a copolymer of styrene, an alkylacrylate such as n-butyl acrylate, and β-carboxyethyl acrylate. Therelative amounts of the monomer components may be adjusted to provide adesired M_(n), M_(w) and/or T_(g). In embodiments, the styrene acrylatecopolymer is characterized by a T_(g) of greater than 50° C., greaterthan 55° C., greater than 60° C., or in the range of from greater than50° C. to 65° C. In embodiments, the styrene acrylate copolymer ischaracterized by a M_(n) of from about 5,000 to about 20,000. Inembodiments, the styrene acrylate copolymer is characterized by a M_(w)in the range of from about 15,000 to about 40,000.

Illustrative examples of other acrylate polymers that can selected forthe high T_(g) amorphous resin include, for example, poly(styrene-alkylacrylate), poly(styrene-alkyl methacrylate), poly(styrene-alkylacrylate-acrylic acid), poly(styrene-alkyl methacrylate-acrylic acid),poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-arylacrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkylmethacrylate-acrylic acid), poly(styrene-alkylacrylate-acrylonitrile-acrylic acid), poly(alkylacrylate-acrylonitrile-acrylic acid), poly(methylmethacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propylmethacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methylacrylate-butadiene), poly(methyl methacrylate-isoprene), poly(ethylmethacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethylacrylate-isoprene), poly(propyl acrylate-isoprene), poly(styrene-propylacrylate), poly(styrene-butyl acrylate), poly(styrene-butylacrylate-acrylic acid), poly(styrene-butyl acrylate-methacrylic acid),poly(styrene-butyl acrylate-acrylonitrile), poly(styrene-butylacrylate-acrylonitrile-acrylic acid), poly(styrene-1,3-diene-acrylicacid), poly (styrene-1,3-diene-acrylonitrile-acrylic acid), poly(styrene-butadiene-acrylic acid), poly(styrene-butadiene-methacrylicacid), poly(styrene-butadiene-acrylonitrile-acrylic acid),poly(styrene-butyl acrylate-acrylic acid), poly(styrene-butylacrylate-methacrylic acid), poly(styrene-butylacrylate-acrylononitrile), poly(styrene-butylacrylate-acrylonitrile-acrylic acid), poly(styrene-butyl methacrylate),poly(styrene-butyl methacrylate-acrylic acid), poly(butylmethacrylate-acrylic acid), poly(acrylonitrile-butyl acrylate-acrylicacid), and mixtures thereof. The alkyl group in the aforementionedpolymers may be any alkyl group, and in particular may be a C₁-C₁₂ alkylgroup, for example including methyl, ethyl, propyl and butyl.

In embodiments, the high T_(g) amorphous resin is an amorphouspolyester. The amorphous polyester may be formed by reacting a diol witha diacid in the presence of an optional catalyst. Examples of diacids ordiesters, including vinyl diacids or vinyl diesters, utilized for thepreparation of amorphous polyesters include dicarboxylic acids ordiesters such as terephthalic acid, phthalic acid, isophthalic acid,fumaric acid, dimethyl fumarate, dimethyl itaconate, cis,1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, maleic acid,succinic acid, itaconic acid, succinic acid, succinic anhydride,dodecylsuccinic acid, dodecylsuccinic anhydride, glutaric acid, glutaricanhydride, adipic acid, pimelic acid, suberic acid, azelaic acid,dodecane diacid, dimethyl terephthalate, diethyl terephthalate,dimethylisophthalate, diethylisophthalate, dimethylphthalate, phthalicanhydride, diethylphthalate, dimethylsuccinate, dimethylfumarate,dimethylmaleate, dimethylglutarate, dimethyladipate, dimethyldodecylsuccinate, and combinations thereof. The organic diacid ordiester may be present, for example, in an amount from about 40 to about60 mole percent of the resin, in embodiments from about 42 to about 52mole percent of the resin, in embodiments from about 45 to about 50 molepercent of the resin.

Examples of diols which may be utilized in generating the amorphouspolyester include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol,2,2-dimethylpropanediol, 2,2,3-trimethylhexanediol, heptanediol,dodecanediol, bis(hydroxyethyl)-bisphenol A,bis(2-hydroxypropyl)-bisphenol A, 1,4-cyclohexanedimethanol,1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol, diethyleneglycol, bis(2-hydroxyethyl) oxide, dipropylene glycol, dibutylene, andcombinations thereof. The amount of organic diol selected can vary, andmay be present, for example, in an amount from about 40 to about 60 molepercent of the resin, in embodiments from about 42 to about 55 molepercent of the resin, in embodiments from about 45 to about 53 molepercent of the resin.

In embodiments, the high T_(g) amorphous resin is an unsaturatedamorphous polyester. Examples of such resins include those disclosed inU.S. Pat. No. 6,063,827, the disclosure of which is hereby incorporatedby reference in its entirety. Exemplary unsaturated amorphous polyesterresins include, but are not limited to, poly(propoxylated bisphenolco-fumarate), poly(ethoxylated bisphenol co-fumarate),poly(butyloxylated bisphenol co-fumarate), poly(co-propoxylatedbisphenol co-ethoxylated bisphenol co-fumarate), poly(1,2-propylenefumarate), poly(propoxylated bisphenol co-maleate), poly(ethoxylatedbisphenol co-maleate), poly(butyloxylated bisphenol co-maleate),poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-maleate),poly(1,2-propylene maleate), poly(propoxylated bisphenol co-itaconate),poly(ethoxylated bisphenol co-itaconate), poly(butyloxylated bisphenolco-itaconate), poly(co-propoxylated bisphenol co-ethoxylated bisphenolco-itaconate), poly(1,2-propylene itaconate), and combinations thereof.

In embodiments, the high T_(g) amorphous resin may be an amorphouspolyester such as a poly(propoxylated bisphenol A co-fumarate) resinhaving Formula III:

wherein m may be from about 5 to about 1000. Examples of such resins andprocesses for their production include those disclosed in U.S. Pat. No.6,063,827, the disclosure of which is hereby incorporated by referencein its entirety.

The cold pressure fix toners may include other components, such as atackifier or another resin, to provide desired bonding performance.Illustrative tackifiers include rosin esters, polyterpenes, terphenephenolics, combinations thereof, and the like. Other illustrativetackifiers include one or more of the following: aliphatic C5 monomerresin, PICCOTAC™ 1095, hydrogenated C5 monomer resin EASTOTAC™ H-100R,EASTOTAC™ H-100L Resin, EASTOTAC™ H-100W Resin, C9 monomer resinsKRISTALEX™ 1120, PICCOTEX™ 75, PICCOTEX™ LC, PICCOTEX™ 100 HydrocarbonResin, styrenic C8 monomers resins PICCOLASTIC™ A5, PICCOLASTIC™ A75,hydrogenated, C9 aromatic monomer resins REGALITE™ S1100, partiallyhydrogenated, C9 aromatic monomer resins REGALITE™ 55100, REGALITE™S7125, REGALITE™ R1100, REGALITE™ R7100, REGALITE™ R1090, REGALITE™R1125, REGALITE™ R9100, mixed C5 aliphatic and C9 aromatic monomerresins PICCOTAC™ 8095, PICCOTAC™ 9095, PICCOTAC™ 7050, aromatichydrocarbon resins, REGALREZ™ 1094, hydrogenated C9 monomer aromatichydrocarbon resins, REGALREZ™ 1085, partially hydrogenated, C9 aromaticmonomer resin REGALREZ™ all from Eastman; Aliphatic C5 modifiedpetroleum resin WINGTACK® 10, WINGTACK® 95, WINGTACK® 98, WINGTACK® 86,aromatically modified petroleum resin WINGTACK® ET and aromaticallymodified petroleum resin WINGTACK® STS all from Cray Valley.Illustrative examples of the resin selected to improve bondingperformance may include, for example, an acrylic, urethane, phenolic,polyamide, polyimide, epoxy, rosin esters, polyterpenes, or mixturesthereof.

In embodiments, the tackifier or another resin is present in the coldpressure fix toner in an amount of from about 1% to about 40% by weightof the total weight of the cold pressure fix toner.

Although other additives may be present in the cold pressure fix toners,in embodiments, the toners do not comprise (i.e., are free of) acolorant. As such, the cold pressure fix toners may be characterized asclear toners.

The cold pressure fix toners can be prepared from the resins describedabove by any means, including conventional extrusion and grinding,suspension, SPSS (Spherical Polyester Toner by Suspension ofPolymer/Pigment Solution and Solvent Removal Method, as described inJournal of the Imaging Society of Japan, Vol. 43, 1, 48-53, 2004),incorporated in an N-Cap toner, or emulsion aggregation. As needed, theresins may be provided as latexes prepared by solvent flash or by phaseinversion emulsification, including by solvent free methods.

The cold pressure fix toners may be used as is or may be formulated intoa developer composition further comprising carrier particles.

Other cold pressure fix toners may be used, including the toners (andcomponents thereof) described in U.S. Pat. No. 9,738,759 and U.S. Pat.Pub. No. 20170017173, each of which is incorporated by reference in itsentirety.

Xerographic Application and Substrate Bonding

As noted above, a first step of the present methods involves disposingany of the cold pressure fix toners on a first substrate (e.g., directlyon the first substrate) in an imagewise fashion via xerography to forman unfused layer of the cold pressure fix toner on the first substrate.The term “xerography” refers to the process of printing via any type ofxerographic printer. Any type of such xerographic printer may be used todispose the cold pressure fix toners on the first substrate. However, inthe first step of the present methods, the cold pressure fix toner isleft unfused, i.e., is not subjected to pressure or heat (or anypressure/heat is sufficiently incidental so that no substantial fusingoccurs). This may be accomplished by using a xerographic printer withthe fusing fixture removed or otherwise disabled.

The term “layer” is not intended to convey a particular shape ordimension. In the xerographic printing of toners, any number of imagesmay be printed. Similarly, the unfused layer of cold pressure fix tonermay assume a variety of shapes or dimensions. In addition, the term“layer” also refers to both continuous layers in which some area of thefirst substrate is entirely covered with the cold pressure fix toner aswell as patterned layers in which some areas of the first substrate arecovered and others are bare. The particular form of the layer dependsupon where adhesion is desired between the first substrate and anoverlying second substrate. The amount of the cold pressure fix toner inthe layer, as measured by toner mass per unit area (TMA), may be in therange of from about 0.1 mg/cm² to 2 mg/cm² or more.

Regarding the first and second substrates, any type of substratematerial may be used provided it is compatible with the selectedxerographic printer. The terms “first” and “second” can refer toindividual, distinct substrates. In other embodiments, the terms canrefer to different portions of the same substrate. By way ofillustration, the cold pressure fix toner may be disposed on a portionof a substrate and the substrate folded to position a different portionof the same substrate over the unfused layer of the cold pressure fixtoner. In addition, this different portion may itself comprise unfusedcold pressure fix toner applied via xerographic printing as describedherein.

After application of the cold pressure fix toner to form the unfusedlayer, the second substrate is placed thereon (e.g., directly thereon).Next, the cold pressure fix toner is subjected to a pressure. This stepmay be accomplished via one or more fixing rolls (e.g., as part of acold pressure fixture) by passing the first and second substrates under(or over or through) the fixing roll(s) at a selected speed.Illustrative fixing rolls include cylindrical metal rolls, whichoptionally may be coated with fluorine containing resins such as TEFLON®PTFE polytetrafluoroethylene resins, TEFLON® PFA perfluoroalkoxy resins,TEFLON® FEP a fluorinated ethylene propylene, DUPONT™ TEFLON® AFamorphous fluoroplastic resins, and silicon resins, or a combination ofthe different resins. Other fixing rolls such as those described in U.S.Pat. No. 8,541,153, which is incorporated by reference in its entirety,may also be used.

Subjecting the cold pressure fix toner to the pressure effectivelyconverts the unfused layer to an adhesive layer, which bonds the firstand second substrates together to form a bonded article. The pressuremay be selected so as to achieve this conversion and thus, this bonding.In embodiments, the applied pressure is about 100 kgf/cm² or greater.This includes embodiments in which the applied pressure is about 200kgf/cm² or greater or about 400 kgf/cm² or greater. In embodiments, noheat is applied during this bonding step (or any heat is sufficientlyincidental so as not to materially affect the bonding process). However,in other embodiments, during this bonding step or after this bondingstep, heat (e.g., via a lamp or the like) may be applied to facilitatebonding.

In embodiments, prior to placing the second substrate on the unfusedlayer of the cold pressure fix toner, an initial pressure may be appliedto the unfused layer of the cold pressure fix toner to partially fix thelayer. However, this initial pressure is generally less than thesubsequent pressure applied to achieve bonding of the first and secondsubstrates. In embodiments, the initial pressure applied to achievepartial fixing is less than about 400 kgf/cm². This includes embodimentsin which the initial pressure applied is less than about 200 kgf/cm² orless than about 150 kgf/cm². The pressure may be applied as describedabove.

The present methods find use in a variety of applications. Illustrativeapplications include the following: sealing documents in which a coldpressure fix toner is applied by xerographic printing onto an edge of aprinted document, the edges are folded together, and the folded edgesare bonded together as described above; peel-apart post cards in which acold pressure fix toner is applied by xerographic printing onto a regionof a postcard (e.g., containing printed information to be hidden), aflap of the postcard is placed over the region, and the flap andpostcard are bonded together as described above; or a peel-to-reveallabel in which a cold pressure fix toner is applied by xerographicprinting onto a region of a label (e.g., containing printed informationto be hidden), a flap of the label is placed over the region, and theflap and label are bonded together as described above.

The bonded articles produced by the present methods are also encompassedby the present disclosure. Thus, in an embodiment, a bonded articlecomprises a first substrate, a second substrate, and an adhesive layerbetween the first and second substrates, wherein the adhesive layer isformed from any of the cold pressure fix toners described herein.

EXAMPLE

The following Example is being submitted to illustrate variousembodiments of the present disclosure. The Example is intended to beillustrative only and is not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated. As used throughout this patent specification, “roomtemperature” refers to a temperature of from about 20° C. to about 25°C.

Two clear cold pressure fix toners were prepared and used as xerographicprintable adhesives for an illustrative demonstration of the presentdisclosure.

Latex Preparation:

A latex of 156.6 nm size was prepared by co-emulsification of a 50/50ratio of a crystalline polyester (C10/C6 CPE(poly-1,6-hexylene-dodecanoate) (AV=10.2 mg KOH/g resin)) and a lowT_(g) polyester resin, a rosin acid-based polyester prepared accordingto Scheme I (GS 1462 (AV=13.5 mg KOH/g resin)). The co-emulsificationwas carried out using a solvent-free phase inversion technique.Specifically, 100 grams of C10/C6 CPE resin, 100 grams of GS1462 resin,9.98 grams of a surfactant, Tayka available from the Tayca Corporation(60 weight %), and 6.69 grams of triethylamine were measured into a 2liter Buchi glass reactor. The reactor was heated to 105° C. over 10minutes. An agitator was started to stir the mixture slowly (around 60rpm) when the reactor temperature was above 65° C. The stirring speedwas increased to 200 rpm when the temperature was above 95° C. and 320grams of deionized water was fed into reactor at around 3.5 grams perminute using an FMI Lab Pump (Model Q3-20). The reactor was cooled downto 25° C. and the latex was discharged and screened through a 25 micronsieve. The resulting resin emulsion was composed of about 37.12 weight %solids in water, and had a volume average diameter of about 167.9nanometers as measured with a HONEYWELL MICROTRAC® UPA150 particle sizeanalyzer.

Toner Preparation:

Into a 2 liter glass reactor equipped with an overhead stirrer 37.39grams of styrene acrylate latex and 140.99 grams of the latex preparedas described above were added. The styrene acrylate latex was 41.72weight % solids in water. The styrene acrylate resin was composed of 79weight % styrene, 18 weight % n-butyl acrylate, and 3.0 weight %β-carboxyethyl acrylate and was characterized by a T_(g) of 63.2° C., anM_(n) of 13,050 g/mole and an M_(w) of 36,562 g/mole. The two latexeswere evenly mixed, the pH of the mixture was adjusted to 2.63 and thenstirred at 4000 rpm using an IKA Ultra-Turrax homogenizer. Next, 19.11grams of aluminum sulphate solution was added dropwise as a flocculentand with continued homogenization. After, the resulting mixture washeated from room temperature to 45° C. at a rate of 1° C. per minutewith stirring at about 200 rpm. The particle size was monitored with aCoulter Counter until the core particles reached a volume averageparticle size of 8.68 μm. Then, 20.54 grams of the same styrene acrylatelatex EP07 was added as shell material, resulting in core-shellstructured particles with a volume average particle size of 8.95 μm.Thereafter, the pH of the reaction slurry was increased to 7.8 using1.74 grams of EDTA (39 weight %) and 18.80 grams of 1 M NaOH solution tofreeze the toner growth. After freezing, the reaction mixture was heatedto 65.0° C. and the pH of mixture decreased to 7.58 using 0.3 M HNO₃.Thereafter, the reaction mixture was maintained at this temperature fora total of 30 minutes for coalescence. The toner was quenched. Theparticles had a volume average particle size of 8.77 μm. The tonerslurry was then cooled to room temperature, separated by sieving (25μm), filtration, followed by washing and freeze dried.

Adhesive Application Procedure:

The toner obtained above was blended with a standard additive packagecontaining 40 nm titania, 120 nm sol-gel silica, 40 nm silica, ZnSt andcerium dioxide. The resulting developer was placed in a modified Color560 printer to generate unfused images (approximately 1.0 mg/cm²) ontoXerox Bold 90 gsm (uncoated) and 120 gsm coated paper. A second sheet ofpaper was then placed on top of the unfused toner before being tested,followed by passing through an in-house cold press fixture (46 mm/s)with the nip pressure set to 1500 psi in order to bond the two sheets ofpaper together. The bonded sheets of paper were peeled apart with a peelforce similar to that provided by the adhesive on Post-It® notes.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations orimprovements therein may be subsequently made by those skilled in theart, which are also intended to be encompassed by the following claims.

What is claimed is:
 1. A method of adhering substrates, the methodcomprising: disposing a cold pressure fix toner comprising a phasechange material on a first substrate via xerography to form an unfusedlayer of the cold pressure fix toner on the first substrate; placing asecond substrate on the unfused layer of the cold pressure fix toner;and subjecting the cold pressure fix toner to a pressure to form abonded article comprising the first substrate, an adhesive layer formedfrom the cold pressure fix toner, and the second substrate.
 2. Themethod of claim 1, wherein, prior to placing the second substrate on thefirst substrate, the method further comprises disposing the coldpressure fix toner on the second substrate via xerography to form anunfused layer of the cold pressure fix toner on the second substrate. 3.The method of claim 1, wherein the pressure applied is about 100 kgf/cm²or greater.
 4. The method of claim 1, wherein heat is applied during orafter subjecting the cold pressure fix toner to the pressure.
 5. Themethod of claim 1, wherein prior to subjecting the cold pressure fixtoner to the pressure, an initial pressure is applied to the unfusedlayer of the cold pressure fix toner to partially fix the layer, whereinthe initial pressure is less than the subsequent pressure applied. 6.The method of claim 1, wherein the phase change material of the coldpressure fix toner comprises a mixture of a low T_(g) amorphous resinhaving a T_(g) of less than about 10° C. and a crystalline organicmaterial having a T_(m) in a range of from about 30° C. to about 130°C., and further wherein the cold pressure fix toner optionally comprisesa high T_(g) amorphous resin having a T_(g) in a range of from about 40°C. to about 70° C.
 7. The method of claim 6, wherein the cold pressurefix toner further comprises a shell over the phase change material, theshell comprising an amorphous resin having a T_(g) in a range of fromabout 40° C. to about 70° C., the amorphous resin of the shell being thesame or different from the high T_(g) amorphous resin.
 8. The method ofclaim 7, wherein the cold pressure fix toner comprises the high T_(g)amorphous resin, either in the phase change material or the shell, andthe high T_(g) amorphous resin has an acid value in the range of fromabout 7 milligrams to about 25 milligrams KOH/gram of resin.
 9. Themethod of claim 7, wherein the cold pressure fix toner comprises thehigh T_(g) amorphous resin, either in the phase change material or theshell, and the high T_(g) amorphous resin is polyester or a copolymerformed from monomers selected from the group consisting of styrene,substituted styrene, alkyl (C1-C6) (meth)acrylates, cycloalkyl(meth)acrylates, (meth)acrylic acid, 2-carboxyethyl acrylate, andmixtures thereof.
 10. The method of claim 6, wherein the low T_(g)amorphous resin is a polyester.
 11. The method of claim 6, wherein thelow T_(g) amorphous resin is a rosin acid-based polyester resin havingFormula I,

wherein R¹ is an abietic acid, a pimaric acid, or combinations thereof;R² is (CH₂)_(n), wherein n is an integer from 2 to 8; A, B, C, and D areindependently selected from hydrogen and methyl; and m is an integerfrom 10 to 10,000.
 12. The method of claim 11, wherein R¹ is selectedfrom dehydro-abietic acid, neo-abietic acid, levo-pimaric acid, pimaricacid, sandaracopimaric acid, iso-pimaric acid, tetrahydro abietic acidand combinations thereof.
 13. The method of claim 6, wherein thecrystalline organic material is an ester compound or a crystallinepolyester.
 14. The method of claim 6, wherein the cold pressure fixtoner further comprises a tackifier or another resin selected from thegroup consisting of an acrylic, urethane, phenolic, polyamide,polyimide, epoxy, rosin esters, polyterpenes, or mixtures thereof. 15.The method of claim 1, wherein the phase change material undergoes achange in physical state from a solid form to a flowable phase having aviscosity lower than about 10⁴ Pa·s at a temperature in a range of fromabout 10° C. to about 90° C., at a pressure in a range of from about 10kgf/cm² to about 100 kgf/cm².
 16. The method of claim 15, wherein thetemperature required to lower the viscosity to about 10⁴ Pa·s at apressure of about 100 kgf/cm² is from about 15° C. to about 70° C. 17.The method of claim 15, wherein the temperature required to lower theviscosity to about 10⁴ Pa·s at a pressure of about 10 kgf/cm² is fromabout 50° C. to about 90° C.